Process of smelting zinc ores.



' bon, which" nnrran STATES PATENT oi rion- I ANSON GARDNER BETTS, OFTROY, NEW YORK.

rrnocnss for simmme zmc cans.

Specification of Letters Patent.

Patented April 20, 1909.

.lipplicationfiled September 26, 1908. Serial No. 454,911.

extraction of provide a method whereby zinc ores containmgimpurities,-suoh as iron or lead, which yield liquid products and causedifficulties in' the usual processes, may be satisfactorily treated? IOther objects willa pear" in connection with the following descriptionof my method.

The reduction of zinc oxid by carbon re-- quires a high temperature ofworking and a large supply of heat at this temperature, and theefliciency of heat supply at, such temperatures is very loW inzinc-furnaces.

My process makes use of the reduction of zinc oxid by other reducingagents than car reduce heat in considerable quantity during thereduction of zinc oxid. Such reducing agents are especially silicon andallo *s thereof and silicids, also alumi nuin, ca clum, magnesium,etc'l, 01 alloys or carblds. thereof. In case of a continuoussmelting'operation, the amount of heat produced by t re reduction'ofzinc oxid in ores or ore products by. such reducing agents is reatenough to keep the temperature of'the urnace wherein the smelting takesplace, several hundred degrees higher than that at which the ore andreducingagent is added.

- The heat of reaction is not however sufficient to also raise thefurnace charge to the smelting temperature.

As carried out in the preferred manner, with silicon'as' the principalreducing agent,

the process is as follows: The ore before or after roasting is mixedwith silicon or a silicon alloy,,as high-silicon ferros1licon,1nquantity suflicient to reduce th'econtained oxids' of zinc, copper,leadjfl and iron, and the mixture heated in areverberatoryfurnace butnot to the temperature at which the reduction of zinc takes place. Thisheating can be safely done in the air or in furnace gases withoutserious oxidation of the silicon.

The heated mixture is passed at high tem-" perature into a highly heatedfurnace. cham-- er, wherein the charge heats up'further and con to takeplace.

amount of heat required to maintain the smelting temperature in afurnace chamber to which the ore and SlllCOIl mixture is addedcontinuously or at intervals, while slag etc.,

are tapped off, is largely reduced or entirely done away with. Thedistilled zinc may be readily condensed with a suitable condenser.-

the reaction commences and goeson. The heat of react-ion is large andthereafter the In distinction from the usual process, the

presence of elements in the ore which yield iquid smelting-productsisnot disadvantaeous, as any liquidfproducts may be tapped rom thefurnace.

used, except at very high temperatures, in distinction from the carbonhitherto used, allows of the ready and economical preheatingof the chare by ordinary furnace methods', for examp e, preheating in areverberfurnace, and even s1mu1taneatory roasting ously roasting the'ore.

. 7 F The unoxidizability of the reducing agent To assist in theformation of thinly fluid slags, Inlay add to the charge fluxes as lime,magnesia, limestone, or'even calcium" carbid,'which latter reacts asreducingiagent The term oxidized as used in the claims means alreadynaturally oxidized, or in case of a sulfid ore, artificially oxidized.The term silicon as used in the claims, except claim 2, includes siliconalloys and silicids.

What I claim as newand' desire to secure by Letters Patent, is

1. The process of treating consists in heating it to a tern eraturebelowthe temperature-of reduction y silicon, and assing a mixture thereofwith silicon into a i rnace wherein vit is further sufliciently 9o zincore which heated to cause the reduction of zinc by si litreating zincore which '2. The process of consists in mixing the ore with a reducing.agent unoxidizable by' air below a temperature of 800 C., heating themixed ore and reducing agent while exposed to the furnace gases by theagency of com ustion, and re-- ducing the ore bythe action of saidreducing agent at ahigher. temperature, and away from the said gases,

. 3. The-process of treating zincore which consists in. mixing the orewith .a reducing agent unoxidizable by air below a temperature of 8000., heating. the mixed ore and reducing agent by the heat ofa'combustion process andredueing the ore by'the"actio1i 1 '5 thereof;and reducing it"at a higher tem era- ;10 the temperature of reductionand reducing of said reducing agent at a "higher temperait at a highertemperature by a material con- -'f f o I tain'mg unoxidized silicon. I

4. The process of treating zinc ore which In testimony whereof I havehereunto consists heating the ore by oxidation signedmy name in thepresence of two subscribing witnesses.

' 'A'NSON GARDNER BETTS.

Witnesses FREDERICK CLARK, BENJAMIN STARBUCK.

ture by a. material containing unoxi zed l silicon. I 1

5'. The process of treating zinc ore which consists in' heating it to a;temperature below

